In a flow cytometer, light is directed onto a stream of sample fluid such that the light impinges and typically excites particles in the sample, causing the excited particles to emit light. The detection of the emitted light provides data that can be analyzed for characterizing the particles and the sample fluid, such as count, physical structure, chemical structure, and other useful information in applications such as for research and clinical purposes. The detection system is therefore a crucial component of a flow cytometer and is a factor in not only the quality (e.g., sensitivity, bandwidth) of the collected data, but also the overall structure and cost of the complete flow cytometer system. In conventional flow cytometers, the detection system includes photomultiplier tubes, or PMTs, which have relatively high sensitivity and high bandwidth, and produces data with relatively low noise. However, PMTs have several disadvantages, such as being relatively expensive and exhibiting temperature drift.
Furthermore, a typical flow cytometer detector has a limited collection range. In simple terms, the collection range of a typical flow cytometer is smaller than the signal range of the objects being analyzed with the flow cytometer. For this reason, the typical detector is supplied with a gain level and/or amplifier. Detectors typically collect data relative to an object's size (light scatter) or brightness (fluorescence); both types of data are often collected on each object detected in the sample. To collect signals from small or faint objects, the gain level is increased. With an increased gain level, however, the signals from large or bright objects are too intense to be collected. To collect signals from large or bright objects, the gain level is decreased. With a decreased gain level, however, the signals from small or faint objects are too weak to be collected. The setting of gain level and other parameters is complicated and difficult. The limitations of the user interface of typical flow cytometer systems have several disadvantages, including: (1) the expenditure of valuable user time spent on the gain-setting process to ensure it is set correctly; (2) the requirement of significantly more sample to determine the proper gain settings; (3) the potential loss of valuable data because at least a portion of input signals are outside of the user-set “active” dynamic collection range and are therefore not collected, and (4) the inability to observe and “undo” changes in user-set gain/scaling settings without running additional samples.
The use of detectors in flow cytometers is also complicated by complex optical systems. To use a conventional optical system, beam splitters and filters must be arranged in a very particular order to properly direct light of particular wavelengths to the appropriate detectors. Rearrangement of the optical system is required whenever a different wavelength detection configuration is required, such as experiments or tests using different fluorochromes. A user must skillfully perform this rearrangement, or the detector system will not function correctly. This limitation prevents the easy swapability of the filters and the easy modification of detection parameters. Further, the particular arrangement of the optical system decreases the reliability and the ruggedness of the flow cytometers, since alignment of the various optical components affects the operability of the detection system.
Thus, there is a need in the flow cytometry field to create new and useful systems and user interface. This invention provides such new and useful systems and user interface for collecting a data set in a flow cytometer.